The brain receives 15% from the cardiac debit in rest and answers for 20% of the total of the corporal consumption of oxygen even so answers for apenas1 a2% of the corporal weight. The sanguineous flow in the brain is normally about 50ml per minute for each 100g of fabric, having regional variations between substances white and cinereous and between different parts of it substantiates gray, this sanguineous flow if it keeps constant in an ample gamma of sanguineous pressures and intracraniana pressure, due to auto-regulation of the vascular resistance. For Kumar; Abbas and Fausto (2205, p.1425) brain is classified as ‘ ‘ …
one weaveeed highly aerbico, with oxygen instead of metabolic substratum serving as substance limitante’ ‘. One knows that the oxygen, substantiates essential for the functioning of the cells that composes the brain, for times can arrive at the fabric cerebral in inefficacious way or even though not to arrive at fabric for any one of some mechanisms: … hipxia functionary in a scene of low partial pressure of oxygen (pO2), comprometimento of the capacity of carry of oxygen for the blood, or inhibition of the use of oxygen for the fabric; or isquemia, transitory or permanent, after the interruption of the normal circulatrio flow.